Analysis of large power systems

Computer-oriented power systems analysis procedures in the electric utilities are surveyed. The growth of electric power systems is discussed along with the solution of sparse network equations, power flow, and stability studies

Silicon Valley in the Polder? Entrepreneurial Dynamics, Virtuous Clusters and Vicious Firms in the Netherlands and Flanders

High-technology starters do not operate in a vacuum and innovation is not a solitary activity. The activities of technology-based firms are embedded in socio-economic networks with other companies, investors, universities, vocational institutions, etc. The geographical proximity of those institutions and infrastructural hubs will partly play a role in determine the location of ICT firms decision. Furthermore, many high-tech companies shape clusters around areas where their major customers are located. The topic of this paper is regional clustering Enright, 1992; Rosenfeld, 1997within the context of Internet and ICT technology. A dynamic model previously developed for the analysis of ICT-entrepreneurship and

Closed Form Solution of Synchronous Machine Short Circuit Transients

This paper presents the closed form solution of the synchronous machine transients undergoing short circuit. That analytic formulation has been derived based on linearity and balanced conditions of the fault. Even though restrictive, the proposed method will serve somehow or other as a new resource for EMTP productivity. Indisputably superior, the closed-form formulation has some features inimitable by discretization such as continuity, accuracy and absolute numerical stability. Moreover, it enables us to calculate states at one specific instant independent of previous states or a snapshot, which any discretization methods cannot do

Evaluation of a coupled hydrodynamic-closed ecological cycle approach for modelling dissolved oxygen in surface waters

The description of intertwined ecological processes in surface waters requires a holistic approach that accounts for spatially distributed hydrological/water quality processes. This study describes a new approach to model dissolved oxygen (DO) based on linked hydrodynamic and closed nutrient cycle ecological models. Long term datasets from the River Dommel (Netherlands) are used to determine: 1) if this methodology is suitable for modelling DO concentrations, 2) the model sensitivity to various levels of nutrients input, and 3) the DO production and consumption processes and their response to nutrient input changes. Results show that seasonal dynamics of DO are well quantified at long timescales; the sensitivity of DO to different pollutant sources exhibits significant seasonal variation and the largest influences on DO are aeration and mineralization of organic material. The approach demonstrates an ability to consider the impacts of nutrient input and long term vegetation maintenance on ecological quality

The All-dq-domain Emtp

This paper presents an improvement to dq-domain method of calculating electromagnetic transients. The proposed methodology works on dq-domain model for all components of the power system and during all time iterations. This is a new direction distinct from the old one where the network is invariably modeled in phase-domain. By modeling the network in dq-domain there is no more problem of interfacing machine to network as usually met in the existing method as machine is modeled invariably in dq-domain. Besides eliminating the time consuming transformation procedure between dq-domain to phase-domain or visa versa the new method is able now to fully exploit the infinite stability region of the trapezoidal rule of integration. The prediction/correction procedure of the conventional dq-domain method, which is notoriously known limiting the stability region, is no longer required. Comparing simulations using the new method and ATP, one of the conventional dq-domain version, show perfect conformity for small time step. For long time step while ATP is failing, the new method still converges accurately up to Nyquist\u27s interval